Liquid dispensing apparatus

ABSTRACT

In apparatus for maintaining in a receiving receptacle a fixed level of liquid introduced by vacuum-restricted gravity flow from a supply reservoir, means are provided for minimizing the disturbance caused by air entry into the vacuum-sustaining space. To this end, a restricted passage for air influx begins at the intended level of liquid in the receptacle and extends with continued restriction to a relatively elevated point of entry into the liquid supply column. Correlation of dimensions of liquid passages and air passages is specified.

O United States Patent 11 1 1111 3,913,61 1 St. John Oct. 21 1975 LIQUID DISPENSING APPARATUS 2,751,928 6/1956 $301k 137/453 Inventor: J G. J Wilton, Conn. 2,847,042 8/1958 emann....-. 222/479 X [73] Assignee: Baldwin-Gegenheimer Corporation, Primary Examiner-Alan Cohan Stamford, Conn. Attorney, Agent, or Firm--St. Onge Mayers Steward & 22 Filed: June 6, 1974 sens [21] Appl. No.: 476,894 [57] ABSTRACT In apparatus for maintaining in a receiving receptacle 52 U S. CL 137/453. 2 2 137/454 a fixed level of liquid iIltl'OdUCfid by vacuum-restricted [51] Int. B 67D 3/00 gravity flow from a supply reservoir means are 5 i l f u 137/453 454 2 1. vided for minimizing the disturbance caused by air 7 '222/437 457 entry into the vacuurmsustaining space. To this end, a restricted passage for air influx-begins at the intended [56] References Cited level of liquid in the receptacle and extends with con- 1 1 tinued restriction to a relatively elevated point of 1 UNITED STATES PATENTS entry into the liquid supply column. Correlation of di- 1,869,258 7/1932 Holland 137/261 x mensions of liquid passages and air passages is Speci 2,139,476 12/1938 Townsend 137/453 X fled. 2,139,477 12/1938 Townsend 137/453 X 11/1949 Potts 222/479 X 3 Claims, 6 Drawing Figures US. Patent OCL 21, 1975 Sheet 1 Of2 3,913,611

WM 7 WM W 2 US. Patent Oct. 21, 1975 Sheet 2 of2 3,913,611

IIVII/II\IIIIIIII l LIQUID DISPENSING APPARATUS The present invention relates to improved liquid dispensing apparatus arid more particularly to apparatus for maintaining in a receiving compartment a relatively fixed level of liquid introduced by vacuum-restricted gravity flow from a supply reservoir. The invention has been found particularlyapplicable to use in the printing industry. i i a BACKGROUND: AND BRIEF DESCRIPTION OF THE INVENTION portions of a particular etch and gum solution are dictated by a number of factors, includingthe type of ink usedsthe nature of the printed work, the color being printed, and the type of paper to be printed.

It has proven impractical to prepare and storelarge quantities of etch and'gum solution over extended periods of time because of the various kinds of deterioration that can occur in the course of such storage. On the other hand, some conditions of press operation may require that relatively great quantities of solution be supplied in a continuous run? To accommodate both these considerations, apparatus has heretofore been provided which can, under automated control, provide a continuous succession; of freshly mixed batches of water and etch and gum concentrate. Such apparatus employs the combination of a reservoir of etch and gum concentrate, almixing chamber in which metered quantities of the concentrate areto be admixed with water (as a customary solvent) and some sort of intermediate metering chamber in which successive measured batches ofconcentrate are temporarily stored as part of themetering process.

In this combinatiomthe primary reservoir of concentrate is conveniently providedin the form of an inverted container which supplies liquid to the metering chamber by vacuum-controlled gravity feed. In sucha system, as concentrate is withdrawn from the metering tank, replacement liquid is automatically fed in from the reservoir somewhat in the manner of the familiar inverted-bottle watercooler. However, for the application of these principles to printing equipment liquid mixing arrangements, itis important, in order to assure accurate metering of the suppliedjconcentrate, that the liquid in flow from the reservoir be relatively smooth and free of the glugging" effect which characterizes many vacuum-controlled gravity feed arrangements. The present invention provides means for assuring this desired resultf.

In the more. general aspect of the invention, this is acincludes a separate restricted passage extending upwardly into the interior of the conduit structure from a point below the said normal liquid level and to a region of the conduit which communicates with the interiorof the reservoir. This passage still further communicates with a relatively small laterally directed airadmitting orifice located approximately at the normal liquid level, so that a slight lowering of the level of the liquid will admit air into the conduit only by successive movement through the orifice and the restricted pas-r sage. It is found that these arrangements prevent the admitted air from causing the serious perturbation of the liquid maintained in the metering chamber and-thus effectively realize the objects of the invention.

Further aspects and advantages of the invention will,

become apparent upon consideration of the following description taken in connection with the accompanying drawings in which FIG. 1 is a perspective view of a mixing apparatus applicable in the printing industry and in which the present invention has been usefully applied. The apparatus of this Figure is fully described in the U.S. Application for Patent Ser. No. 47l ,208, filed May 20, 1974, in the names of John MacPhee and Harold W. Gegenheimer,

which application is hereby incorporated by reference j in the present application. a

FIG. 2 is a partial sectional view of the apparatus of FIG. 1 showing a specificapplication of the invention.

FIG. 3 is a sectionalized view of a particular embodiment of the present invention.

FIG. 3. a

FIG. 5 is an enlarged section FIG. 3. a

FIG. 6 is a greatly enlarged irregular section taken on line 6-6 of FIG. 3.

taken on line 5-5 of DETAILED DESCRIPTION or THE INVENTION Referring to-FIG. I there is shown in that Figure the external configuration of any assembly of particular liquid mixing apparatus representing an advantageous application of the invention. This assembly has as its base portion a receptacle or tank 10 whichis so formed as to be readily self-supported upon any level surface.

This tank consists of a molded enclosure of liquid and etch-resistant plastic material, for example, polyvinyl I of the'apparatus, to be admixed with water or other apcomplished byprogviding between the superposed reservoir and the meteringchamber into which it feeds a a conduit assemblywhich includes in the first instance a passage through which liquid from the reservoir is admitted to thetank at a point below the intended normal surface level of the liquid pool to be maintained in the tank. Beyond ,this, howeverQthe conduit system further propriate diluent or solvent. For present purposes it is sufficient to notethat the container 30 as illustrated comprises a water-tight and air-tight assembly consistmaintaining the end walls in firm assembly with the cylindrical sidewall 32. In the inverted position in which it is shown the container 30 has a downwardly directed FIG. 4 is an enlarged section taken on line 4 4 of outlet st m40 (seerilo fz'i hicj egdesc ribed.

in detail atalafterpo n able" normallyis'ecu'red casings and 46 which enclose electrical a in'eehanical cont'rol' aeyice fm which some furtheri referjehee be made at 'a later point; A wat'er supplyjpipe 48is1'also ope'rative'ly connected" w and throu'gh' the cover plate, 20, and there'i's further supplied a control assembly for controlling the proportions of the liquid rnix'whichfit is the flinction 'ofth over-all assembly re 'prediifc. A t the right y there is shown a liquid handiextrernity'of the 'assembl outlet conduit'60.

Referring 'nowtoFl G. 2, in'which many of the items so'fai' described will be readilyidentified, itwill be seen that thetank' 10 as viewed in longitudinal section com prises' a -first' liquid-receiving "compartm'ent'70 which 1 occupies the greater portion of the right handpart of thetank structure and has wing portions'70'a extending to the'left endof the structure. It isthe function of this compartment to receive a substantial quantity of a pri mary liquid- (e.g. water) which in thecourse'of operation "of the apparatus is to be admixed with a secondary constituent sn'cli an etch and gum concentrate; -To the leftof this first'compartment, but'in proximity to it,

there is provided a second, smallercompartment 75,

the wall structure or which 'isshown as being formed continuouslyiiwith :the wall structure of: the compartm'ent370; ltsis the=function of thiscompartment to re-i ceive from the reservoir the secondary liquid*or.con-- centratezThiszsecond liquid isintroducedinto the com-' partment 75 from the reservoir 30 by means of the 'outlet system 40; already referred to, The-details, of this outlet system comprise the present invention and will; I

therefore-'bedeseribedindetail at a later point. .It is sufficient at this point, however, to say that the conduit system has a primary out let 25 2 through which downflowing'liciuid frb m thereservoir '30-is supplied to the chamber 75: The combination of ,the inverted: reservoir 39' and the; outlet system, 40 provides a-Jiquid level maintaining system of the type in yvhichlhe balance between the ,ar-tial .yacuuni existing in the upper portion of the .re servoir 3Qand the weight of the liquid column seekingegress throughtheoutlet 252 causes a substan-, tially. constant levelof liquid to be, rnaintained.;in the chamber-75, as indicated at7 8,

As maybe recognized by joint consideratien of 1 and 2, the compartm ent 75 isan open top receptacle orbasin. having a bottomwalljSaformed with considerable spacing between it and the supporting foundation of the total tank ajssembly .10. On three sides of this float 80, comprising a body material having a significantly lower-specific gravity thanwater. On its upper surface, there is attached a stainless steel plate bearing an upwardly. extending U-shaped bracket 85. This bracket has vertical legs 85a and atransversle part 85b joinin'g these legs. At the eentral regioniof thetransverse part there is a slot 850 extending at right angles to the axis of the transverse part. I

There is supported well above the central region of '10 the float-block 80 andwithin the cover-mounted casing 44 a two-way toggle' switch -88having a power connected contact 8g and two alternatively usable contacts 8 8band 88c. It may beassumed that these connect with control means (.not shown) for-alternativ ely supplying water to and releasing water from the tank 70. An operative connection, between the switch 88 and the float block 80 is provided by means of a push rod 90 which 'at it'supper endis connected to the switch actuator,8 8f by a: member 91 coacting with a fixed mounting bracket 92. The rod extendsdown 'Wardly through the slot 85 c inthe transverse bracketf part 85b so that its lower end approaches but does not-1 contact the plate 82. Circular ,collars 93 n and,93b are 70) a point will be reachedatwhich theftransverse bracket part 85b will engagethe collar 93b and cause the push rod to move the switch actuator into uppermost position. This action will snap 'the power;

connected switch element 8 8 iz'into contact with switch terrninal 88c. ln the intended use fof the apparatus, this will' simultaneously'cut"off the incoming supply of water re "the tank com'partment' '70 and will initiate an out-flow'of water through'the 'conduit 60 (FIG 1), thus lowering the water level in the tank.

Because, previously indicatedithe 'siivitch '88is'of an over-center variety, the reduction in water level will not immediatelyaffect the condition of the switch.

However, when the float 80 has' dropped significantly basin is lateral bounding ,,wall is connected to and mergesjnto the boundingwall of the tank 70 means ofahorizontal bridging part. .75b. The narrow extensions 704. of the,,compartment 70 extend along and in effect enclose the lateral walls of the compartment 75; i

It will be apparent that by virtue of this arrangement the;'compartmen t 75 has'a pointv above which liquid contained in that ,eo'mpartment lwill overflow the bounding surface 75b and drop infothelargerinixing compartment.

The elements, at

between a predetermined minimum level'and tennined inaximum level an w n-be described iiiy' I the rig ht of'FlG. 2 illustrate m eans' 'i bywhieh the liquid in the tank [rn'1 y be maintained brieflynbecause they do not bearfdirectly on theisub f stance of the present invention. These means include '(i.e., with decreasing water 'level) a'point will be reached at which the transverse bracket part 18 5b'will contact the upper surface of the rodcollar 93 ki, thus drawing therod inthe downward direction. Wherithis happens, the switch 88 will be thrown into. its alternate position with the contacts 88a and 88b in engagement. Under theselcircumstances, the outflow of water from the compartment 70 will e halted andtheinflux or a fresh supply of 'water will begin. This cycle will con-' tinue indefinitely unless interrupted by the operator of the equipment. It'will be understood that the maximum and niinimuml'ev'els which the water is permitted to attaincan be predetermined in advanceby up and down adjustment of thef'rod -borne collars 9 3n 'and 93b.

Having now described briefly the system of :water level control provided inconnection with the primary tank compartment" 70, it is'in order 'next 'to indicate with similar brevity the mean's by which this system also functions to control'the supply'of measured quantities of etch and gum solution from the secondaryftank'co'm r a'rirhen't' For such control, each of the vertical float a't tachedfbracket parts a is provided with a pair of spaced pivot pins an'd 141. Each of the upper ones 'of these pins has rotatably secured to it a lever arm 145 which is further rotatably secured to and supported by a fixed fulcrum provided by a pin or bolt 147. Each of these bolts 147 is in turn heldin place by a vertical bracket 148 having a secure attachment to the cover plate 120 of the assembly. Each lever arm extends some distance to the left of the fulcrum pm 147, being provided near its left extremity with an upwardly directed notch 155. Each of the notches is adapted to engage (from below) a horizontally extending support bar 160 shown in sectionin FIG. 2.

Each of the vertical bracket parts 85a has further attached to it a second lever arm 165 pivotally mounted on one of the bolts 141. This lever arm extends between the bracket 85a and the bracket 148, being pivotally attached to the latter by a pin or bolt 170. The

two identical level arms 165 are connected at their right hand extremities by a bridging piece 165b with which they jointly form a U-shaped assembly having its open end directed to the left. The combination of the fixed vertical brackets 148, the levering members 145 and 165, and the float-attached brackets 85a provide at each end of two opposed extremities of the float 80 a pantograph arrangement the effect of which is to assure that the bracket parts 85a remain perpendicular to the floor of the tank compartment 70 as the float moves up and down. This in turn maintains the major surfaces of the float parallel with the floor of the tank and prevents the float from assuming an angular position which might cause it to frictionally engage any of the tank wall surfaces.

By action of the lever arm 145, motion of the float 80 is enabled to produce measured transfer of etch and gum concentrate (or other activating liquid) from the secondary tank compartment 75 to the primary compartment 70. This is accomplished by means of a displacement block or piston 200 which is associated with compartment 75 and which may be assumed to be generally cubic in form. The block extends over only a portion of the area of the compartment 75, leaving adequate clearance for the liquid conduit assembly 40, and is constituted of an appropriate liquid resistant material having specific gravity of about 1.4. Because of the latter characteristic it will tend .to sink in the liquid 78 contained in the compartment 75 unless it is supported by means other than its buoyancy in the liquid. The supporting means actually employed comprises in the first instance the horizontal bar 160, to which the piston is attached by spaced eye-bolts 205. The openings in these bolts are dimensioned to permit the piston to swing freely on the bar 160.

The bar itself has two separate means of support. The first of these comprises the pair of notched lever arms 145 to which reference has already been made. The second comprises another pair of lever arms 210 (one only being shown) which are joined in a U-shaped assembly by a cross-member 210b extending between them at their right hand extremities. The assembly is provided with oppositely disposed fulcrum points by extensions of the bolts or pins 147 supported in downwardly extending bracket arms 148. By virtue of this arrangement, downward movement of the cross member 2l0b will lift the piston-supporting extremities of the lever arms 210. These extremities, in turn, are provided with upwardly directed notches (not apparent in the drawing) which are formed toreceive. the extremities of the support bar 160.

It is the function of the lever arm 210, coacting with additional means now to be described, to limit the possible downward motion of the displacement block or piston 200 without regard to the maximum upward motion of the float 80, and thus to permit controlled variation 'of the quantity of secondary liquid which the piston can cause to overflow the compartment 75. This is to be accomplished without concurrently altering the total quantity of primary liquid supplied to compartment 70. These objectives are achieved by providing operator-controlled means for adjusting the degree to which the left hand ends of the lever arms 210 can be drawn down by the weight of the displacement block 200. The particular means provided for this purpose comprises a circular blocking member 220 affixed to the lower end of a vertical adjusting rod 225. This blocking member engages the upper surface of the lever-connected cross-bar 21% when the cross-bar reaches a certain level, that level being variable in accordance with the degree of downward extension of the adjusting rod 225. Upon such engagement of parts, downward motion of the displacement block 200 necessarily ceases regardless of its degree of submersion in the etch and gum solution 78. Assuming that a predetermined quantity of solution has been deposited in the compartment before downward motion of the displacement block begins, it will be apparent that limitation of downward motion of the block automatically determines the fraction of this quantity which will be caused to overflow the boundary surface 75b, and thus effectively meters the amount of concentrate which can flow into intermixing relationship with the liquid in compartment 70. I

As further appears in FIG. 2, the adjustment rod 225 is supported from the tank cover plate 20 by a fitting 227, which is internally threaded to engage external threads provided on the adjustment rod. Near its upper end the rod is provided-with a knurled knob 228 by which it can be screwed up anddown in the fitting 227. A pointer 229, also attached to the upper end of the rod, (although not rotatable with it) coacts with a scale 231, marked with appropriate measurements (e.g. fluid ounces per gallon) so that, after initial calibration of the system, the location of the pointer will indicate how much liquid is to be expelled from compartment 75 during a single cycle of operation of the apparatus. The amount can be increased at any time by turning the knob 228 to raise the blocking plate 220 to a degree indicated by the change of position of the pointer 229. Conversely, the amount can be reduced by effecting downward motion of the blocking plate.

While the lever arms 210 and the blocking plate 220 conjointly fix the limits of motion of the piston 200, the occurrence of such movement in the first instance depends primarily upon action of the earlier described lever arms 145. In this connection, it may be assumed, for example, that the apparatus at the end of a filling and mixing cycle is in the condition in which it is shown in FIG. 2. It will be seen in this Figure that the float is at a high level, corresponding to attainment of the maximum desired level of the primary fluid. Under these conditions, the lever arms have disengaged the piston support bar 160 as they are free to do because of the open notches by which engagement of the arms and the bar are accomplished. The piston thus remains supported solely by the independent lever arms 210. Consider, however, that the next phase of operation of the apparatus involves draining liquid from the compartment 70. As such drainagev occurs, the float 80 will fall and the left hand extremities of the lever arms 145 will rise. At a certain point, the notches 155 will re-engage the cross-bar 160 and, in effect take over from the lever arms 210. In the preferred mode of operation of this system, the piston will be lifted by the lever arms 145 (i.e., as actuated by the falling float 80) until it nearly (but not quite) leaves the surface of the liquid in the compartment 75. As this occurs, the level of liquid in the compartment 75 will tend to fall below its intended normal level this being because part of the liquid required to sustain that level has been displaced into the compartment 70 by the prior .downwardmotion of the piston. Accordingly, replenishment from the supply reservoir 30 will be called for. The way inwhich this is accomplished by the present invention will now be described.

Referring now more particularly to FIG. 3, it will be seen that the supply connection between the reservoir 30 and the compartment 75 comprises the conduit assembly 40, previously referred to. It should be noted first that to permit occasional refilling of the reservoir, the assembly 40 is removable as a .whole from the reservoirs end wall 36 by means of ya screw thread 241 formed at theupper end of the hollow conduit or cylinder 242 of relatively large cross-section which. forms the enclosure of the assembly. This thread engages a corresponding thread provided internally on a mouthforming sleeve 39 which is attached to the reservoir end wall and which in use extends downwardly through an appropriately sized opening formed in the tank cover of FIG. 2. A gasket 241a forms a tight seal be tween the end of the sleeve 39 and an annular flange 242a secured to the outer surface of cylinder 242. The threaded end of the cylinder242 encloses .in tightfittingv engagement a second cylinder or sleeve 243 which has an inwardly tapered or countersunk end surface 243a. This is adapted to receive an interfitting closure member or stopper 244 which in turn is attached to an axially extending push rod 246. This rod is of such length that when the reservoir 30 is put in place on the tank cover (FIG. 2), the lower end of the rod will engage the floor of the tank compartment 70 as indicated at 246a. In consequence, the stopper 244 is pressed away from the tapered opening 243a and liquid is free to flow into the cylinder 242 through a comparatively open connectiomOn the other hand, when the reservoir is moved away from the tank assembly (for refilling or otherwise), a compression spring 249 appropriately located at the lower end of the rod immediately pulls the stopper into closed position, thus permitting the reservoir to be lifted and turned into an upright position without loss of liquid. This feature is not new in itself and is not described as novel. However, at the lower end of the cylinder 242, there are provided novel means for controlling the release of liquid into the tank compartment 75. These means include in the first instance a cylindrical block 250 interfitted within the bore of the hollow cylinder 242. This block has a central opening for the rod 246 and two additional circular openings or holes 250a and 250b. The first of these receives a tubulation 252 which, in the illustrated orientationof theapparatus, extends downwardly below the intended level-,of the liquid 78 in the compartment 75 and provides a restricted outlet for liquid from the resreceives at its upper end, a second tubulation 254 which is crimped and closed I atits upper extremity as indicated at 254:: and which has in the sidewall of the crimped region arelatively small circular orifice 255. Through the openingthusfprovided, the liquid within the cylinder 242 is in communication with the main body of fluid in the tank compartment not only through the tubulation 252 and the lower end of the opening 250b but also through a small passage provided by the bounding wall of a lateral orifice 256 which is located with its center line at the intended equilibrium level of the liquid pool 78. The effect of this arrangement is, first of all, that as long as a supply of liquid concentrate remains in the reservoir 30, the level of such liquid maintained in the receiving compartment 75 tends to stabilize at approximately the midpoint of the opening 256. That is to say, as long as the liquid pool 78 is at or above the statedlevel, the air inlet path provided to the container 30 through the still exposed part of the opening 256 is too restricted (by water surface tension or otherwise) to permit air bubbles to enter the enclosure 242. Accordingly, no air reaches the upper region of the container 30, and the partial vacuum maintained in that region prevents liquid from being released into the compartment 75, either through the tubulation 252 or through the lower end of the opening 250b.

However, once the displacement piston 200 (FIG. 2) has been lowered sufficiently to cause a significant amount of liquid concentrate to overflow into the mixing compartment and has thereafter been re-elevated by the weighted float 80 (i.e., upon the withdrawal of solution from the mixing compartment), the liquid remaining in the compartment 75 will (in the absence of replacement) fall below its original level. Once this begins to occur, the opening 256 will become fully uncovered, and a stream of small air bubbles will flow through the passages formed by and between the opening and the orifice 255 into the upper reaches of the container 30. In this way, the vacuum in the container will be broken, so that liquid may be released through the tubulation 252. This will continue until the liquid level in compartment 75 again reaches the midpoint of the opening 256, at which time air flow will cease and a new condition of stabilization will exist.

The liquid control system just described provides special advantages in avoiding large scale surges of inrushing air and out-rushing liquid at any time. That is to say, the succession of small air bubbles which develops inthe restricted path formed by the openings 256 and 255, taken in connection with the restricted liquid flow which can voccur through tubulation 252, precludes the severe glugging effect often encountered in vacuum-controlled liquid feed systems. This in turn prevents the occurrence of perturbation or fluctuations in liquid level in compartment 75 sufficiently violent to cause liquid concentrate to slop over the wall surface 75b (FIG. 2) and thus to produce unpredictable variations in the proportions of the solution formed in compartment 70. It is believed sufficient for operability in this fashion that the openings 255 and 256 and the opening in tubulation 252 be specified as relatively small in proportion to the cross-section of the main passage within the cylinder 242. In a particular case good results .have been obtained with a construction in which the cylinder 242 has an internal bore of about 1 inch,

ervoir 30 into the compartment 75. The opening 2507b" 7 Q and the openings 252, 256, 255 and 250b measure 3/16 inch, 3/16 inch, /4 inch and inch, respectively. While the invention has been described by reference to a specific embodiment, it will be understood that numerous variations may be made by those skilled in the art. For example, it is believed that for operation with large liquid handling systems, the dimensions specified in the preceding paragraph can appropriately be scaled up proportionately. Also, while circular passages have been employed for convenience in manufacture, other shapes having comparable cross-sectional areas can alternatively be adopted. It is therefore intended in the appended claims to cover all modifications which fall within the true spirit and scope of the invention.

What is claimed is the following.

1. For use in a vacuum-controlled gravity-feed liquid dispensing system of the type in which a superposed reservoir supplies liquid to an underlying receptacle to maintain a relatively fixed level of liquid in the receptacle, an improved assembly for feeding liquid between the reservoir and the receptacle, said assembly comprising:

A. a main conduit of relatively large cross-section having at one end a compartively open connection with the supply reservoir for both conducting air to the supply reservoir and for conducting liquid from the supply reservoir; and

B. means partially blocking the other end of said main conduit but providing 1. a first passage by which liquid flowing from the supply reservoir into said main conduit may be admitted to the receptacle at a point below the intended normal surface level of said liquid in the receptacle;

2. a second passage of relatively limited crosssection opening at a point below the intended normal surface level of liquid in the receptacle, said second passage defining a. a first laterally directed orifice of relatively restricted cross-section communicating between the interior of said second passage and the interior of said main conduit to complete an open connection between a point below the intended normal surface level of liquid in the receptacle and the interior of the main conduit; and

a second laterally directed air admitting orifice of relatively restricted crosssection located to have its center line approximately at the normal surface level of the liquid and communicating with the interior of said second passage, so that a slight lowering of the liquid will admit air through the main conduit by successive movement through said second orifice, said second passage and said first orifice.

2. An assembly according to claim 1 in which A. the main conduit is a hollow tubular member;

B. the said blocking means is a solid body conforming to the interior dimensions of the said tubular member;

C. the first passage comprises a first hole formed lengthwise through the solid body and terminating in a restricted outlet;

D. the second passage comprises a second hole formed lengthwise through the solid body, terminating at its upper end in means providing said first restricted orifice for the flow of air from the second hole into the main conduit.

3. An assembly according to claim 1 in which said means providing said first restricted orifice is a tubulation crimped and closed at its upper extremity having upper extremity. 

1. For use in a vacuum-controlled gravity-feed liquid dispensing system of the type in which a superposed reservoir supplies liquid to an underlying receptacle to maintain a relatively fixed level of liquid in the receptacle, an improved assembly for feeding liquid between the reservoir and the receptacle, said assembly comprising: A. a main conduit of relatively large cross-section having at one end a compartively open connection with the supply reservoir for both conducting air to the supply reservoir and for conducting liquid from the supply reservoir; and B. means partially blocking the other end of said main conduit but providing
 1. a first passage by which liquid flowing from the supply reservoir into said main conduit may be admitted to the receptacle at a point below the intended normal surface level of said liquid in the receptacle;
 2. a second passage of relatively limited cross-section opening at a point below the intended normal surface level of liquid in the receptacle, said second passage defining a. a first laterally directed orifice of relatively restricted cross-section communicating between the interior of said second passage and the interior of said main conduit to complete an open connection between a point below the intended normal surface level of liquid in the receptacle and the interior of the main conduit; and b. a second laterally directed air admitting orifice of relatively restricted cross-section located to have its center line approximately at the normal surface level of the liquid and communicating with the interior of said second passage, so that a slight lowering of the liquid will admit air through the main conduit by successive movement through said second orifice, said second passage and said first orifice.
 2. a second passage of relatively limited cross-section opening at a point below the intended normal surface level of liquid in the receptacle, said second passage defining a. a first laterally directed orifice of relatively restricted cross-section communicating between the interior of said second passage and the interior of said main conduit to complete an open connection between a point below the intended normal surface level of liquid in the receptacle and the interior of the main conduit; and b. a second laterally directed air admitting orifice of relatively restricted cross-section located to have its center line approximately at the normal surface level of the liquid and communicating with the interior of said second passage, so that a slight lowering of the liquid will admit air through the main conduit by successive movement through said second orifice, said second passage and said first orifice.
 2. An assembly according to claim 1 in which A. the main conduit is a hollow tubular member; B. the said blocking means is a solid body conforming to the interior dimensions of the said tubular member; C. the first passage comprises a first hole formed lengthwise through the solid body and terminating in a restricted outlet; D. the second passage comprises a second hole formed lengthwise through the solid body, terminating at its upper end in means providing said first restricted orifice for the flow of air from the second hole into the main conduit.
 3. An assembly according to claim 1 in which said means providing said first restricted orifice is a tubulation crimped and closed at its upper extremity having said first orifice in the region of the crimped enclosed upper extremity. 